You’re on a good track because you have a great idea of what “rolling” means (car tire). “Rolling over” on your back implies that you’re already laying down, however, you’re not laying on your back (maybe you’re laying on your side) and you roll your body to change your position so that you’re on your back (to look at the sky 🌈). 🤗 Nicky

It means the person was lying on their stomach, facing the ground, and "rolled" (like a ball) 180° so they were lying on their back facing upwards. Think lying in bed facing the ceiling.

When a person "rolls over" it means they are lying down and they turn their body so that a different part is facing upward. In this case, the person turned so that their back was facing the ground and the front part of their body was facing the sky. I hope this explanation helps. Good luck, Mryoso!

that is correct. rolling over means something moving forward for example your body in a turning or rotating position.